<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<h1>注册成功</h1>
	</body>
	<script type="text/javascript">
		var str = "我爱门北京天安门";
		var str2 = "天安门上太阳升";
		var str3 ="qwcdWEVERqsdsdac"
//		console.log(str[6])
//		console.log(str.concat(str2));
//		console.log(str2.indexOf("门"));
//		console.log(str.replace("门","广场"));
//		console.log(str.slice(-6,-3));
//		console.log(str.split(""));
		console.log(str.substr(3,3));
		console.log(str.substring(3,6))
		var xiao =	str3.toLowerCase()
		var da = str3.toUpperCase()
		console.log(xiao)
		console.log(da)
	</script>
</html>
